1. Field of the Invention
The present invention relates to an optical communication system, and more particularly to an optical switch employed in the optical communication system.
2. Description of Related Art
With rapid development in fiber optics communication, optical fibers are widely embedded all over the world, so as to provide wider bandwidth and better reliability than copper wires, microwave relays and satellites do. An optical communication system includes a large number of optical switches for transmitting signals through specific network routes. The optical switch is capable of selecting one of the optical fibers and alternatively aligning ends of two optical fibers, such that light beams can be transmitted from one of the optical fibers to the other.
The optical switch should be characterized by high reliability, low insertion loss, low back reflection, and so forth. The insertion loss may reduce the strength of the signals, while reflected signals may result in crosstalk effects. Accordingly, in order to comply with demands on operating the optical switch, the ends of the two optical fibers should be aligned in both an axial direction and a horizontal direction. Due to a small position tolerance of the optical fibers of the optical switch, the alignment of the optical fibers is rather time-consuming during the process of manufacturing the optical switch, leading to an increase in the production costs.
Referring to FIG. 1, a fiber optic switching apparatus 100 disclosed in the U.S. Pat. No. 6,385,365 includes two alignment heads 112 and 114, two output optical fibers 122 and 124, and an input optical fiber 130. An end 122a of one output optical fiber 122 is mounted in a V-groove 112a of the alignment head 112, while an end 124a of the other output optical fiber 124 is mounted in a V-groove 114a of the alignment head 114. Besides, a movable end 130a of the input optical fiber 130 is located between the two V-grooves 112a and 114a. In a first condition, the end 130a of the input optical fiber 130 is aligned to the bottom end 122a of the output optical fiber 122.
FIG. 2 is a side view illustrating the optical switch of FIG. 1 in a second condition. Referring to FIGS. 1 and 2, in order to align the end 130a of the input optical fiber 130 depicted in FIG. 1 to the end 124a of the upper output optical fiber 124, the fiber optic switching apparatus 100 further includes a relay 140 to uplift the end 130a of the input optical fiber 130. Accordingly, as the end 130a of the input optical fiber 130 is elevated by the relay 140, the end 130a of the input optical fiber 130 can be aligned to the end 124a of the upper output optical fiber 124, as shown in FIG. 2.
On the contrary, as the end 130a of the input optical fiber 130 is lowered down by the relay 140, the end 130a of the input optical fiber 130 can be again aligned to the end 122a of the bottom output optical fiber 122. Therefore, light beam signals can be alternatively transmitted from the input optical fiber 130 to the output optical fiber 122 or 124 by adopting the relay 140 for arranging the positions of the output optical fibers 122 and 124 relative to the position of the input optical fiber 130.
However, during the process of respectively assembling the output optical fibers 122 and 124 to the alignment heads 112 and 114, the relative positions of the alignment heads 112 and 114 and the relative positions of the output optical fibers 122 and 124 are in great variations, and thus the difficulty of assembling the fiber optic switching apparatus 100 is then increased.
Further, U.S. Pat. No. 6,385,365 discloses an alignment head having a through hole in a diamond shape for defining two output optical fibers. In spite of omitting the alignment between two alignment heads, the single alignment head having the through hole in the diamond shape is still not able to alleviate difficulties of assembling the optical fibers in an effective manner.
Besides, another optical switch using the relay to control the position of the input optical fiber relative to the positions of the output optical fibers is disclosed by U.S. Pat. No. 6,044,186. However, said patent is not conducive to reducing the complexity of assembling the optical fibers. Since the main production costs of the optical switch lie in labor hours spent on assembling the optical fibers, it is imperative to reduce the production costs by alleviating the difficulties of assembling the optical fibers.